Why such a simple thing has to be so complex? Did you have a problem with selecting just a equal M43 lens?

I'm still can't fathom the depth of idea behind setup

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Camera in bag tends to stay in bag...

Umm, you seem to have completely missed what these focal reducers do. They are designed to adapt full frame or (some) APS-C lenses to smaller formats by shrinking the image circle, which has the added benefit of reducing the effective aperture of the lens. You couldn't attach an MFT lens to a focal reducer because it would make the image circle smaller than the sensor.

Well, if I understand you right, speed booster is a focal reducer, and it takes from FL and,shrinking an image circle, adds to an F-stop making lens faster.

Am I right? If I'm, than all these

1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones."

are just different brands of the same FL reducer, and there are 4 different setups. OP wants to compare different brands, which may make a sense.